Lithium-ion batteries are presently limited by the electrical capacity of graphite electrodes, affecting their storage power. From that point of view, metal oxides such as SnO
2 are a promising alternative to graphite. Their behavior during the charge-discharge cycles can be improved due to nanoscale structuring and doping: a nanostructure multiplies the contact surface and fosters the diffusion of lithium. Furthermore, doping can increase the electrical conductivity of the material.
Researchers have synthesized nitrogen-doped tin oxide nanoparticles, by laser pyrolysis in the presence of ammonia. With these nanopowders, they crafted anodes for accumulators and assessed their electrochemical performances.
Even in the absence of doping, these anodes turn out to be much better than the state of the art, due particularly to SnO2 composites that incorporate carbon. The optimal doping is obtained for nitrogen content of 3% (in atoms).
This work, funded by "Advanced Materials", a CEA transverse program, was carried out in collaboration with Nanyang Technological University in Singapore as part of a thesis under joint supervision.